Ann Thorac Surg 2001;72:S1059-S1064
© 2001 The Society of Thoracic Surgeons
Supplement: Cardiothoracic techniques and technologies
Modified button-Bentall operation for aortic root replacement: the miniskirt technique
Guido Michielon, MDa,
Loris Salvador, MDa,
Uberto Da Col, MDa,
Carlo Valfrè, MDa
a Cardiac Surgery Department, Ospedale S. Maria dei Battuti, Treviso, Italy
Address reprint requests to Dr Michielon, Cardiac Surgery Department, Ospedale Bambino Gesú, P.zza S.Onofrio 4, 00165 Roma, Italy
e-mail: guido.michielon{at}tin.it
Presented at the Seventh Annual Cardiothoracic Techniques and Technologies Meeting 2001, New Orleans, LA, Jan 24–27, 2001.
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Abstract
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Background. The aim of this study was to evaluate the midterm results of a modified button-Bentall operation (modified-bB) specifically designed to incorporate any type of prosthetic valve in composite conduit aortic root replacement.
Methods. Between 1991 and 2000, a total of 135 patients underwent modified-bB for annuloaortic ectasia (74 patients), type A dissection (31), or aortic aneurysm without dissection (30). Of these, 34 were emergencies (25.2%). A total of 50 bioprostheses (study group 1) and 85 bileaflet mechanical prostheses (study group 2) were implanted. Group 1 mean age was 66.9 ± 7.4 years versus 51.5 ± 12.1 years in group 2 (p < 0.001). Composite-conduit creation occurred during proximal suture line construction as a single-step maneuver. Interrupted extracardiac polyester mattress sutures sequentially entered the aortic annulus, the prosthetic valve ring, and the vascular graft 7 mm from its free edge (miniskirt). Running monofilament suture line secured proximal hemostasis, buttressing aortic remnants and graft edge. Coronary reimplantation was accomplished in all cases by the button technique. Concomitant procedures were performed in 51 patients (37.8%).
Results. The 30-day mortality was 5.18% (7/135 patients). Eight patients (5.9%) required revision for proximal (1 patient), coronary button (3), or distal (4) anastomosis leakage. Three patients (2.2%) perioperatively developed nonfatal inferior myocardial infarction. Kaplan-Meier 9-year survival is 91.8% ± 0.026 SE with 88.1% (95% confidence limits 71.7% to 95.5%) reoperation freedom. According to the Cox proportional hazard method, stratification of the risk for death according to prosthesis type indicates previous operation (p = 0.001) and emergency (p = 0.0465) as independent predictors of hospital mortality. Associated procedures to modified-bB increased risk of reoperation (p = 0.031).
Conclusions. Modified-bB was associated with low mortality, excellent midterm survival, and freedom from reoperation. Absence of valve-to-graft tapering, reduced coronary button anastomosis tension, and prosthesis selection according to patient profile, are apparent advantages of modified-bB.
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Introduction
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Since the original description of the Bentall-DeBono procedure in 1968 [1], composite graft replacement of the aortic root has become a generally accepted means of surgical therapy for a variety of aortic root pathologies. Advancements in surgical technique and tissue preservation have continued to provide the surgeon with several alternative surgical options in the treatment of aortic root disease [2–5]. The aim of this study was to retrospectively review the results with a modification of the button-Bentall operation (modified-bB) specifically designed to incorporate any kind of prosthetic valve device in the root replacement procedure.
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Material and methods
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Between August 1991 and September 2000, 135 consecutive patients (102 male and 33 female) underwent aortic root replacement (ARR) by a modified-bB (Fig 1A, 1B, and 1C), incorporating either a bioprosthesis (50 patients, group 1) or a bileaflet mechanical prosthesis (85 patients, group 2). A Hancock II porcine xenograft (Medtronic, Minneapolis, MN) was used in 48 patients, whereas a stentless Toronto SPV (St. Jude Medical, St. Paul, MN) was selected for 2 patients. The bileaflet mechanical prostheses implanted in group 2 patients included the following prostheses: SJM (St. Jude Medical) in 23 patients, Carbomedics (Sulzer Carbomedics, Austin, TX) in 49 patients, and Sorin Bicarbon (Sorin Biomedica, SpA, Italy) in 13. The mean age was significantly different in group 1 (66.9 ± 7.4 years) versus group 2 (51.5 ± 12.1 years) (p < 0.0001). The ARR was performed as an emergency procedure in 34 patients (25.2%), on an urgent basis (next available operating list) in 8 patients (5.9%), and electively in 93 patients (68.9%). Indications for surgery included the following: annuloaortic ectasia with pathologic findings consistent with cystic medial necrosis and aortic valve (AoV) insufficiency in 74 patients; either acute (30 patients) or chronic (1 patient) type A aortic dissection with massive AoV incompetence; combined AoV stenosis and insufficiency associated with extensive involvement of the aortic sinuses (22); prosthetic AoV dysfunction with aortic root aneurysm (6); and prosthetic AoV endocarditis (2 patients). The AoV was congenitally bicuspid in 27 patients (20%). In all, 20 patients (14.8%) had undergone previous cardiac surgery and 5 patients were respectively at the third (4 patients) and fourth (1 patient) median sternotomy. Aortic valve replacement had been undertaken in 8 patients, graft replacement of the tubular segment of the ascending aorta in 6, combined AoV replacement and graft replacement of the ascending aorta in 3, mitral valve (MV) replacement in 1, and coarctation repair through a left posterolateral thoracotomy in 2. Four patients developed a type A aortic dissection and underwent a modified-bB a mean of 52.2 months after previous AoV or ascending aortic surgery. A modified-bB was performed for aortic root aneurysm with progressively severe AoV incompetence in 4 other patients at a mean time interval of 63.2 months after repair of a type A aortic dissection by interposition graft replacement of the tubular ascending aorta with AoV preservation.
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Fig 1. Miniskirt technique. (A) The aneurysmal aorta has been resected and the coronary buttons prepared. Proximal suture-line construction and composite conduit creation from separate prosthetic valve and vascular graft are accomplished with a single-step maneuver. Interrupted extracardiac mattress sutures sequentially enter the aortic annulus, the valve ring and the vascular graft, approximately 7 mm from its free edge. (B) Proximal hemostasis is secured with a running monofilament sutureline, buttressing aortic remnants, native aortic valve leaflets (when preserved) and graft edge. (C) Coronary reimplantation is accomplished according to button technique in all patients.
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Operative details
Aortic root replacement was performed by means of a full median sternotomy in 134 patients and a J sternotomy in 1 patient. Femoral arterial cannulation was selected in 58 patients (42.9%) and aortic arch cannulation in the remaining 77 patients (57.1%). Antegrade or retrograde cold blood cardioplegia was infused after aortic cross clamping. The redundant aortic tissue was excised and the coronary buttons prepared. The composite conduit was created from separate prosthetic valve and woven polyester tube graft during proximal suture-line construction. Interrupted extracardiac polyester mattress sutures sequentially entered the aortic annulus, the prosthetic valve ring and the vascular graft, 7 mm from its free edge (Fig 1A). The native aortic valve leaflets were preserved and laterally displaced in open position outside the tube graft in 68 patients (50.4%). A second running monofilament sutureline secured hemostasis, buttressing aortic wall remnants, native valve leaflets (when preserved), and graft edge (Fig 1B). Coronary reimplantation was performed according to the button technique in all patients (Fig 1C). The distal anastomosis was telescoped to the divided aorta and externally reinforced with Teflon felt (Bard, Inc, Billerica, MA). Concomitant procedures were performed in 51 patients (37.8%) and included: coronary artery bypass grafting (13 patients), repair of dissected coronary ostium (14), MV replacement (6), MV plasty with PTFE chordae implantation (2), ASD suture closure (2), subaortic membrane resection (1 patient), aortopulmonary fistula closure (1), internal carotid thromboendoarterectomy (1), and aortic arch (4 patients) or hemiarch (8) replacement. Deep hypothermia (21.1°C mean rectal temperature) and circulatory arrest were planned in 20 patients to perform an open distal anastomosis (8 patients) or to replace the aortic arch (12). Selective antegrade (11) or retrograde (3) cerebral perfusion was accomplished during circulatory arrest in 14 patients. The mean duration of circulatory arrest was 23.4 ± 11.8 minutes. Gelatin-resorcin-formaldehyde glue was used in to facilitate layer apposition of the dissected aorta or dissected coronary ostia.
Follow-up
All group 2 patients received long-term anticoagulation with warfarin, whereas a 3-month warfarin prophylaxis was followed in the majority of group 1 patients. Only 5 (10%) group 1 patients are currently on long-term anticoagulation, mainly due to chronic atrial fibrillation (4 patients). After hospital discharge, the patients’ clinical status was evaluated at regular intervals (6 months, then every year) at the outpatient clinic. Follow-up information was available for all hospital survivors except 1 (99.3% complete). Total follow-up was 411 patient-years; the mean follow-up for all hospital survivors was 36.54 months (range 2.4 to 113 months).
Statistical methods
Kaplan-Meier survival and freedom from reoperation were calculated using the SAS Procedure Lifetest (SAS release 6.12 TS020; SAS Institute, Cary, NC). Selected endpoints were death, reoperation, or percutaneous transluminal coronary angioplasty (PTCA). Dichotomous variables were analyzed by the 
2 and Wilcoxon rank-sum tests. Variables associated with increased risk of hospital and late death were assessed by univariate and multivariate logistic regression analyses and by Cox proportional risk multivariate analysis (SAS procedure PHREG). Hazard modeling of survival and freedom from reoperation according to the Blackstone method [6] were conducted to evaluate the presence of a late risk phase in the model.
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Results
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Mortality
Hospital mortality was 5.18% (7/135 patients). Of the 7 deaths, 5 occurred after emergency ARR; 4 of these patients had had previous sternotomy. Causes of death were cardiac failure (2 patients), untreatable ventricular arrhythmia (3), sepsis (1 patient), and stroke (1). Two patients with prosthetic valve endocarditis developed stroke (1 patient) and sepsis (1) and died after emergency ARR. In both cases an allograft of adequate size was not available, and the infected aortic root was replaced incorporating a bioprosthesis in the modified-bB. Three patients died early after modified-bB for sustained ventricular arrhythmia; indication for surgery was acute type A dissection in 2 patients, and the dissected ostium of the right coronary artery was repaired in 1 case. The third patient was known to have noncritical stenosis of the obtuse marginal branch of the circumflex and of the right coronary artery. Coronary bypass grafting was not associated in that case. Low-output syndrome was the cause of death in the remaining 2 patients. One of these patients presented in cardiogenic shock and cardiac tamponade after a type A dissection involving the aortic arch and the right coronary ostium. He underwent a combined modified-bB, aortic arch replacement and right coronary artery bypass grafting; however, he never recovered satisfactory hemodynamics and died the following day because of low output. The other patient was known to have a degenerated and stenotic aortic bioprosthesis, an aneurysmal aortic root, severe mitral valve insufficiency, depressed systolic function (EF 42%), and an LV end-diastolic volume index of 131 mL/m2. He underwent combined modified-bB and mitral valve replacement, with preservation of the subvalvular apparatus of both the anterior and posterior mitral leaflets; however, he developed low output after surgery and died the following day. Hospital mortality was 1.07% (1/93 patients) in the group undergoing elective procedures, 14.7% (5/34 patients) in the emergency operation group, and 20% (4/20 patients) in the group of patients with previous cardiac surgery. According to Cox proportional hazard multivariate analysis, the independent predictors of hospital death were previous operation, emergency procedure, and use of a bioprosthesis (Table 1). However, the mean age of group 1 patients was 15.4 years higher than in group 2. Stratification of the risk of death according to prosthesis type confirmed previous operation and emergency procedure as independent predictors of hospital mortality in both groups. Late mortality was 2.3% (3/128 patients). Two patients had had previous operation for a type A aortic dissection. In the first case, the false lumen extended to the right femoral artery and a modified-bB was accomplished after GRF-glue reapposition of the dissected aortic layers, proximal to the innominate artery take-off. The second patient had had his ascending aorta previously replaced with an interposition graft, resuspending a moderately insufficient AoV. He subsequently developed an aortic root aneurysm proximal to the vascular graft, progressively severe AoV insufficiency, and a thoracoabdominal aneurysm without evidence of residual dissection distal to the innominate artery. He underwent an uncomplicated modified-bB and died 2 years later while awaiting replacement of his thoracoabdominal aorta. Autopsy was allowed and was significant for rupture of the descending thoracic aorta in both cases. The third patient, a 76-year-old woman, died suddenly at home 2.3 years after a modified-bB for annuloaortic ectasia. Permission for autopsy was not obtained; however, this patient was known to have a thoracoabdominal aneurysm at the time of modified-bB. Currently 124 patients are alive (91.8%). Kaplan Meier actuarial survival is 84.4% ± 0.058 SE in group 1 versus 96.0% ± 0.024 SE in group 2 (p = 0.017) (Fig 2A). Overall Kaplan Meier survival is 91.8% ± 0.026 SE at 9 years. The nomogram of hazard function for death and reoperation according to Blackstone and colleagues [6] indicates an early, rapidly declining phase of hazard with no appreciable late phase, probably due to the low number of events (Fig 2C and 2D).
Morbidity
Reexploration for bleeding was necessary in 13 patients (9.6%) and a surgical source was identified in 8 patients (5.9%). Bleeding occurred at the proximal suture line in 1 patient, at the coronary button anastomosis in 3 patients, and at the distal aortic suture line in 4. Distal leak was more common in modified-bB for type A dissection (3/4 patients, 75%), whereas coronary leak occurred in modified-bB for annuloaortic ectasia (3/3). Proximal leak occurred in a third redo operation for prosthetic AoV dehiscence. Transient neurologic deficit developed in 3 patients early after surgery and in 2 other patients after hospital discharge, whereas a permanent deficit occurred in 4 patients (3%), with 50% mortality. There was no association between use of circulatory arrest or prosthetic valve type selection and occurrence of neurologic events. Three patients (2.2%) with annuloaortic ectasia experienced a perioperative myocardial infarction after modified-bB, with no early or late death. Myocardial necrosis was documented by electrocardiographic, enzymatic, and echocardiographic changes, and was localized to the inferior wall in all 3 cases. Intraaortic balloon counterpulsation was necessary and successful in 2 patients. One patient required permanent pacemaker implantation 2.3 years after modified-bB.
Reoperations
Eight patients underwent reoperation (7 patients) or PTCA (1 patient) at a mean interval of 21.7 months after modified-bB. Reoperations included CABG (1 patient), redo Bentall for proximal pseudoaneurysm (1), repair of distal pseudoaneurysm and CABG (1), pericardiectomy for constrictive pericarditis (1), renal transplant for chronic renal failure (1), resection of abdominal aortic aneurysm (1), and valve thrombectomy (1 patient). No pseudoaneurysm occurred at the coronary button suture line. There was one valve-related complication in a 30-year-old woman with a bileaflet mechanical prosthesis, who reduced her anticoagulation regimen during an unexpected pregnancy and developed prosthetic valve thrombosis. She underwent successful surgical thrombectomy on cardiopulmonary bypass during the second trimester and eventually delivered a full-term, 2.8-kg baby boy without complications. All reoperations occurred in group 2 patients. Freedom from prosthetic valve endocarditis is 100% at 9.4 years. Currently, no bioprosthesis has been explanted due to tissue failure. Among the 128 hospital survivors, the reoperation freedom is 88.0% at 9.4 years (95% confidence limits [CL], 74.7% to 98.3%) (Fig 2B), and the event-free actuarial survival (ie, freedom from death or any invasive procedure) is 85.2% at 9.4 years (95% CL, 71.7% to 95.5%). The occurrence of a procedure associated with the modified-bB was the only independent predictor of risk of reoperation (Table 1).
Thromboembolism, anticoagulant-related complications, and functional status
Follow-up information was available on 127/128 hospital survivors (99.2% complete). In more than 411 patient-years of follow-up, 8 patients had late nonfatal complications related to anticoagulant therapy (1.9% per patient-years). There were two late nonfatal thromboembolic events, accounting for a thromboembolic rate of 0.48% patient-year, and six spontaneous bleeding episodes requiring hospitalization and transfusion (1.42% patient-year linearized rate). Currently, 115 patients are in New York Heart Association class I (92%) and 9 are in class II. Moreover, 43 patients (52.4%) in group 2 returned to work.
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Comment
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Since the first description by Bentall and DeBono [1] of an inclusion technique for composite graft replacement of the aortic root, advancement in surgical technique, prosthetic material, and tissue preservation have provided the surgeon with a variety of surgical options in the treatment of aortic root disease [2–5]. The introduction of the button-Bentall procedure by Kouchoukos and associates in 1981 [2] was specifically designed to avoid pseudoaneurysm formation at the site of the aortic or coronary suture lines. Kouchoukos and associates identified an 8.5% incidence of pseudoaneurysm formation after the original Bentall operation with 45% mortality at reoperation for pseudoaneurysm repair. The availability of cryopreserved aortic and pulmonary allografts, as well as the recent introduction of stentless roots, have broadened the surgical strategies for aortic root replacement with aortic allograft, pulmonary autograft, or porcine roots. Aortic valve sparing procedures have been introduced [5] to preserve normal aortic valve leaflets in case of valve dysfunction secondary to dilatation of the sinotubular junction or dilatation of the sinuses of Valsalva. However, the availability of aortic and pulmonary homografts is limited, leading to precise indications for allograft aortic root replacement and Ross operation. Therefore, replacement of the aortic root with a composite conduit can be considered a valid surgical option when extension of aortic root pathology appears to prevent aortic valve sparing procedures. We have used composite conduit ARR in acute dissections (24%) when the intimal tear deeply extended into the aortic sinuses, or when it was located in a preexisting aneurysm; in Marfan syndrome or cystic medial necrosis with annuloaortic ectasia and overstretched aortic leaflets (54%); in patients undergoing AoV replacement with extensive involvement of the aortic sinuses (16%); and in cases of prosthetic AoV dysfunction with associated aortic root disease (6%). However we have repaired or preserved the aortic valve in most cases of aortic dissection or when an aortic valve sparing operation was indicated, while an aortic homograft was preferred in active young patients, or in the case of infective endocarditis. Composite conduit ARR is a complex procedure, especially when conducted on friable tissues as an emergency operation. Hemostasis and tension-free coronary ostia reimplantation represent the key points for surgical success. Most commercially available composite grafts currently combine a bileaflet mechanical valve within a prosthetic graft. Our criticism of this choice is twofold. First, the intraoperative measurement of the aortic annulus will determine sizing of both prosthetic valve and vascular graft. However, these dimensions may not be correlated, and coronary displacement may be macroscopic in the case of annuloaortic ectasia with massive enlargement of the sinuses of Valsalva. Late complications associated with the Cabrol operation [7], resulting from graft limbs kinking or intimal hyperplasia [8], have discouraged us from considering this procedure even in the setting of reoperation. Second, long-term anticoagulation in the elderly may not be desirable for its associated morbidity. We have designed a modification of the button-Bentall operation that allows the construction of a composite conduit from separate prosthetic valve and polyester vascular graft. In the rationale for this surgical approach, prosthetic valve selection, valve sizing, and vascular graft sizing become completely independent variables. The idea of ARR with a home-made conduit is not new and was usually accomplished as a two-step procedure: the sewing ring of the aortic prosthesis was first joined to a tube graft, and the home-made composite conduit was then sutured to the native aortic annulus. Our technical modification allows composite conduit creation and proximal suture line construction as a single-step maneuver. Moreover, the proximal suture line is reinforced with a running monofilament suture line incorporating aortic wall remnants, valve leaflets, and graft edge, therefore improving proximal hemostasis. A 5.18% hospital mortality in this cohort favorably compares with that of 5% to 13% in other reported series [9–13]. Series comparison is often difficult, however, as patient profiles and the prevalence of emergency procedures such as aortic dissection and reoperations may be significantly different. Hospital mortality was 1.07% (1/93 patients) in the group undergoing elective procedures, 14.7% (5/34 patients) in the emergency operation group, and 20% (4/20 patients) in the group with previous sternotomy. Previous operation, emergency procedure, and use of a bioprosthesis were identified as independent predictors of hospital mortality. However, the mean age in group 1 was 15.4 years higher than in group 2, and stratification of the risk of death according to prosthesis type confirmed previous operation and emergency procedure as independent predictors of hospital mortality in both groups. The nomogram of hazard function for death showed an early, rapidly declining phase of hazard with no appreciable late phase, probably due to the low number of events. Late mortality was 2.3% (3/128 patients), mainly due to progression of disease in other segments of the thoracic aorta. A 91.8% Kaplan-Meier survival at 9 years, with a mean follow-up of 3.05 years (range, 0.1 to 9.4 years), favorably compares with other series, including those in which higher-risk patients (ie, emergency cases) have been excluded [14]. Morbidity was low in this. Revision for a surgical source of bleeding occurred in 5.9% patients. The technical modification that we suggest might have an impact on proximal and coronary button suture line performance. Leak at this combined level occurred in 2.9% patients. Proximal leak occurred in the case of a third redo operation for prosthetic AoV dysfunction, whereas a coronary button leak occurred in 3 patients with annuloaortic ectasia and macroscopic cephalic displacement of the coronary ostia. This underlines the issue of coronary reimplantation technique in ARR. In the modified-bB, size selection of the vascular graft is independent from prosthetic valve size, and we therefore used slightly larger vascular grafts in case of gross displacement of the coronary ostia. The idea is to have the vascular graft "reaching out for" the coronary buttons instead of having the coronary buttons "looking for" the graft, which may result in undue tension on the coronary anastomosis. This allowed us to reimplant the coronaries according to button-technique in all patients, with a 2.2% revision for surgical bleeding at this level, 2.2% mortality for ventricular arrhythmias, 2.2% morbidity for coronary insufficiency resulting in nonfatal myocardial infarction, and a 2.34% rate of myocardial revascularization procedures after modified-bB, but no late incidence of coronary-button pseudoaneurysm formation. Perioperative myocardial necrosis was localized to the inferior wall in all patients, suggesting a special attention to reimplantation of the right coronary button. Freedom from reoperation was 88% at 9 years (95% CL, 74.7% to 98.4%). The occurrence of procedures associated with the modified-bB was the only independent predictor of risk of reoperation.
In conclusion, the modified-bB operation was associated with low mortality and morbidity, excellent midterm survival, and freedom from reoperation. Independent selection of the vascular graft and prosthetic valve sizes eliminates the potential for valve-to-graft tapering, reducing the tension on coronary-button anastomosis. The reinforced proximal suture line potentially improves hemostasis. Prosthesis selection can be designed according to the individual patient’s profile. In the case of reoperation for prosthetic valve dysfunction, prosthetic valve replacement can be accomplished as an isolated procedure, thereby respecting the previously reconstructed aortic root.
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Acknowledgments
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The authors acknowledge the technical assistance and expertise of Dr. Marina Negri for the statistical review and data analysis of this study cohort.
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References
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Top
Abstract
Introduction
= mechanical prostheses; 
= bioprostheses; 
= overall; dashed lines = overall upper confidence limits (UCL) and lower confidence limits (LCL). (B) Actuarial freedom from reoperation. No further events occurred after 70-month follow-up from modified button-Bentall.